Spheres of Water

Water and oil do not form a solution that can be mixed. In
most cases, you see ample amounts of water with a small surface
layer of oil. However, in this reverse situation where droplets
of coloured water have been placed in an oil solution, the
results are depicted in the photo. The hydrophobic nature of the
oil causes the coloured water to be repelled and to take on a
spherical shape, since this provides the least surface
area-to-volume ratio. Since the density of water is greater than
oil, the drops sink to the bottom of the container. However, a
few smaller water droplets remain at the surface due to the
surface tension of the oil molecules. As more water droplets were
added, the smaller droplets would become larger due to cohesion
and would sink to the bottom.